Automated media storage library with variable focal length lens

ABSTRACT

A bar code reader for an automated storage library has a lens assembly with a pair of polarized liquid crystal lenses. Each lens has pair of parallel glass plates that are separated by upper and lower glass substrates. A series of polymer films are symmetrically spaced apart between the substrates. Both the substrates and the films are perpendicular to the glass plates. Electrodes are formed on the films and combine to form a semi-cylindrical stack of film. Liquid crystal fills the spaces between adjacent pairs of the films. The films are coated and/or treated by an alignment process to predispose the liquid crystals to a specific rotational direction. When a selected voltage is applied between adjacent ones of the electrodes, the liquid crystals are synchronously rotated to alter their refractive index to a desired value. Thus, when the layers of each lens are manipulated in unison, the bar code reader is able to quickly adjust its focal length to read bar codes at various distances.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] This invention relates in general to automated media storagelibraries and in particular to an automated media storage library with avariable focal length lens for scanning bar coded labels associated withdata storage media in the library.

[0003] 2. Background Art

[0004] Automated media storage libraries which utilize storage devicessuch as data cartridges are well known in the art. A large number of thecartridges are typically mounted in a rotatable housing or magazine andindividually indexed with bar coded labels. The labels may be positionedin a variety of locations, including on the cartridges themselves,adjacent to a mail slot on the housing, or on a door around each mailslot. A bar code reader system is located adjacent to the housing forreading the labels so that the desired cartridge may be selected andaccessed. In order to scan a label associated with a moving cartridgeand/or reader system, the focal length of the reader must be adjustableto accommodate for cartridges and labels which differ in size and, thus,distance from the reader. This problem has become even more acute withlibraries which contain multimedia storage devices.

[0005] Therefore, it is a feature of the present invention to provide anassembly with a high speed, variable focal length lens for reading barcode labels on media devices located in an automated media storagelibrary.

SUMMARY OF THE INVENTION

[0006] A bar code reader for an automated storage library has a lensassembly with a pair of polarized liquid crystal lenses. Each lens haspair of parallel glass plates that are separated by upper and lowerglass substrates. A series of rectangular polymer films aresymmetrically spaced apart between the two glass substrates. Both thesubstrates and the films are perpendicular to the glass plates. Asemi-circular electrode is formed on each side of each piece of film toform a semi-cylindrical “stack” of film. The electrodes do notcompletely cover the film. Liquid crystal fills the space between eachadjacent pair of the films. The films are coated and/or treated by analignment process to predispose the liquid crystals to an alignment androtation direction.

[0007] When a selected voltage is applied between adjacent ones of theelectrodes, the liquid crystals are synchronously rotated to alter theirrefractive index to a desired value. Thus, when the layers of each lensare manipulated in unison, the bar code reader is able to quickly adjustits focal length to read bar codes labels on media devices at variousdistances. For example, when the applied voltage is zero, there is norefractive index difference between the electrode portion and thenon-electrode portion of the liquid crystal. Therefore, the focal lengthis infinite. Applying a voltage to the electrodes alters the refractiveindex of the liquid crystal and, thus, shortens the focal length of thelens assembly to the proper distance for reading the labels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the features, advantages and objectsof the invention, as well as others which will become apparent, areattained and can be understood in more detail, more particulardescription of the invention briefly summarized above may be had byreference to the embodiment thereof which is illustrated in the appendeddrawings, which drawings form a part of this specification. It is to benoted, however, that the drawings illustrate only a preferred embodimentof the invention and is therefore not to be considered limiting of itsscope as the invention may admit to other equally effective embodiments.

[0009]FIG. 1 is an isometric view of a lens assembly constructed inaccordance with the invention.

[0010]FIG. 2 is an isometric view of a single liquid crystal (LC) lensof the lens assembly of FIG. 1.

[0011]FIG. 3 is a schematic, sectional side view of the LC lens of FIG.2.

[0012]FIG. 4 is a schematic top view of the LC lens of FIG. 2 takenalong the line 4-4 of FIG. 3.

[0013]FIG. 5 is a front view of the LC lens of FIG. 2 showing a firstconfiguration.

[0014]FIG. 6 is a front view of the LC lens of FIG. 2 showing a secondconfiguration.

[0015]FIG. 7 is a schematic, enlarged, sectional side view of a portionof the LC lens of FIG. 2 shown without an applied voltage and takenalong the line 7-7 of FIG. 4.

[0016]FIG. 8 is a sectional side view of the portion of the LC lens ofFIG. 7 shown with an applied voltage.

[0017]FIG. 9 is an isometric view of an automated media storage librarythat incorporates the lens assembly of FIG. 1 and is constructed inaccordance with the invention.

[0018]FIG. 10 is an enlarged front isometric view of a cartridge stationof the library of FIG. 9 wherein the door of the station is open.

[0019]FIG. 11 is a schematic front isometric view of the cartridgestation of FIG. 10 with the door closed.

[0020]FIG. 12 is a schematic, rear isometric view of the cartridgestation of FIG. 11.

[0021]FIG. 13 is a schematic, rear isometric view of an alternateembodiment of the cartridge station of FIG. 11.

[0022]FIG. 14 is a schematic drawing of a method for making the LC lensof FIG. 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] Referring to FIG. 1, a sensor or lens assembly 11 for use with abar code reader in an automated media storage library 12 (FIG. 9) isshown. Lens assembly 11 comprises a front liquid crystal (LC) lens 13, arear LC lens 15, and a transparent spacer plate 17 therebetween. A laserlight source 19 (indicated schematically by the arrow) is projected intorear lens 15 from right to left. Light source 19 is independentlyfocused by each lens 13, 15 into a conical beam 23, 25, respectively,and focused to a common point 21 to the left of front lens 13. Thethickness of spacer plate 17 is selected to be one half of onewavelength of the light emitted by light source 19.

[0024] Lenses 13, 15 are identical in construction and are isillustrated in detail in FIGS. 2-4. For simplicity, only lens 13 will bediscussed even though the following description applies equally to lens15. Lens 13 consists of a pair of parallel, glass plates, 31, 33, and aplurality of thin, rectangular, insulative, polymer films 35therebetween. In the embodiment shown, plates 31, 33 are 1 mm squares.The inner surfaces of plates 31, 33 are spaced apart by 70 microns whichis also the width of films 35. Each film 35 has a length of 1 mm and athickness of 2 microns. A pair of glass substrates 41, 43 are located atthe upper and lower ends, respectively, of lens 13 with films 35therebetween. Films 35 and substrates 41, 43 are parallel to oneanother, and perpendicular to plates 31, 33. Films 35 and substrates 41,43 are evenly spaced apart from one another by 50 microns. Thus, in theembodiment shown, there are 19 films 35 which define 20 layers betweensubstrates 41, 43.

[0025] The upper and lower surfaces of each film 35 and the innersurfaces of substrates 41, 43 have an electrode 45 formed on them. Inthe embodiment shown, electrodes 45 are semi-circular in shape with aradius of 2 mm, but they may be formed in any other shape that alsowould produce a positive focal length. As will be discussed below, theradius of electrodes 45 is determined by the range of focal lengthsrequired by the application. Although electrodes 45 have a thicknessthat is less than 10 nm, they are shown much thicker for illustrationpurposes. Electrodes 45 may be sputtered to the desired shape with apatterned mask, or sputtered over the entire rectangular surface offilms 35 and substrates 41, 43, and then chemically etched with apatterned photo-resist to obtain the desired shape. Other processes,such as photolithography, may also be used to obtain the desired patternfor electrodes 45.

[0026] After electrodes 45 are formed, an alignment material (not shown)is spin-coated or printed on top of the electrodes and the remainingsurface area of the underlying substrate. The most popular alignmentmaterial for liquid crystal is polyimide. However, any material forhomogenous parallel alignment, such as polyvinyl alcohol, may be used.The alignment material has a thickness of 30 nm or less. After thealignment material has coated the electrodes and their substrates, analignment process, such as rubbing, is performed on the alignmentmaterial to set the desired alignment direction for the liquid crystals.Other alignment processes, such as photoalignment, which establishparallel homogenous alignment may also be used.

[0027] The alignment effect from the surface of the substrate is limitedto several dozen microns (approximately 30 to 70 microns). Therefore,films 35 are mounted in spacers (not shown) to maintain their 50 micronspacing. The spacing between films 35 could be larger or smaller, aslong as the alignment effect is maintained. The films 35, substrates 41,43, and plates 31, 33 are then assembled together to form lens 13 beforethe liquid crystals 47 are injected into the spaces or cells.

[0028] Note that the total thickness of each film 35, including anelectrode 45 and outer layer of alignment material on each surface(which are substantially negligible at 20 nm and 60 nm total) isapproximately 2 microns. Since there is only one film 35 for every 50microns of transmission width, the amount of light transmitted by lensassembly 11 is diminished by only 4% per lens 13, 15, or 8% total.

[0029] Referring to FIG. 14, lens 13 is assembled by dispensing heatcurable epoxy resin 37 around the perpendicular glass plates 31, 33,films 35, substrates 41, 43 and spacers to form a seal 38 therebetween.An opening 39 in the lens body assembly 13 is reserved for injecting theliquid crystals 47. After curing the epoxy, the liquid crystals 47 areinjected through opening 39 into the cells between films 35 with avacuum injection technique. The air in the cells is removed with a pump40 to create a vacuum and opening 39 in seal 38 is immersed into theliquid crystals 47 to fill the cells by capillary action. Opening 39 issealed after the lens 13 is filled.

[0030] As shown in FIGS. 5 and 6, liquid crystal 47 fills the spacesbetween films 35 and substrates 41, 43. FIGS. 1, 5 and 6 also show theperpendicular orientation of lenses 13, 15 relative to one another andthe lens assembly 11 overall. In the embodiment shown, the layers offront lens 13 are vertically oriented, and the layers of rear lens 15are horizontally oriented to form a polarized lens assembly

[0031] Each lens 13, 15 can only focus in one direction, hence, lenses13, 15 are rotated and fixed at 90 degrees relative to each other.Spacer plate 17 is required for two-dimensional focusing. For example,referring to the Cartesian coordinate system 67 in FIG. 1, lens 13 couldcontrol focusing in an Y-plane angle of light beam 19, while lens 15controls the Z-plane angle. Thus, the coaxial direct-ion is theX-direction.

[0032] Referring now to FIGS. 3, 7, and 8, the leads 51, 53 of a voltagesource 55 are connected to electrodes 45 in an alternating pattern. Afocal length controller 57 is provided for controlling the voltage ofvoltage source 55. Although both electrodes 45 on each film 35 have thesame the same orientation, the adjacent films 35 (both above and below)have the opposite orientation so that the liquid crystal 47 lyingtherebetween is exposed to the voltage potential. Thus, the liquidcrystal 47 in each cell or space between the films 35 may be manipulatedsimultaneously and in unison. The amount of voltage required tomanipulate liquid crystals 47 is minimized as the spacing between films35 is only 50 microns.

[0033] Note that electrodes 45 do not extend across the entire width offilms 35 and substrates 41, 43. In the embodiment shown, electrodes 45only cover about two-thirds of the surface area of their respectivesubstrates. Thus, a portion of the birefringent liquid crystal 47 lyingbetween adjacent films 35 (above and below the left sides of films 35)is not subjected to the voltage potential in order to vary the focallength of lens assembly 11. Since, the minimum focal length is 10 mm andthe difference between the ordinary (left side) and extraordinary (rightside) refractive indexes of liquid crystal 47 is about 0.2, the radiusof electrodes 45 must be no larger than the product of the focal lengthand the index difference (hence, 10 mm× 0.2=2 mm radius).

[0034] In FIG. 7, the applied voltage is zero, so liquid crystals 47 areidentically aligned and oriented on both sides of films 35 (only twofilms shown). In FIG. 8, the applied voltage does not equal zero, so thealignment direction of the liquid crystals 47 on the right side of films35 are proportionately reoriented, and the liquid crystals 47 on theleft side of films 35 remain unaffected. This changes the refractiveindex of the liquid crystals 47 and, thus, the focal length of lensassembly 11.

[0035] Note that since lenses 13, 15 are spaced apart from each otheralong the X-axis, the voltages applied to them must be different inorder to focus at the same X-axial point 21. The focal length of lens 15should be longer than that of lens 13. Since the difference in the focallengths is fixed by the configuration, the relation of the appliedvoltage to lenses 13, 15 can be calculated. Controller 57 calculates theapplied voltages to lenses 13, 15 according to the information from thebar code reader. For example, if the focal length of lens 15 is 15.0 mm,and the total thickness of spacer plate 17 and lens 13 is 5.0 mm, thefocal length of lens 13 would be 10 mm. Lenses 13, 15 focus light 19simultaneously to a single point 21.

[0036] In operation (FIGS. 9-13), library 12 has a base 61 containing aplurality of drives (not shown) and a door 63 with an opening 64. Door63 is pivotally mounted to base 61 and is normally closed, but shownopen in FIG. 9. A mail slot or cartridge input/output (I/O) station 65is mounted to door 63 (shown exploded from door 63 in FIG. 9). Station65 has a generally cylindrical, stationary body or magazine 71 with acoaxial door 73 that is pivotable or rotatable about the Z-axis relativeto body 71. Door 73 has a generally cylindrical shape and is shown openin FIG. 10 and closed in FIG. 11. Magazine 71 has a plurality ofparallel, cartridge storage slots 75, each of which may contain one ormore data cartridges 77 (two shown). Cartridges 77 may comprise tape,magneto-optical disk, digital versatile disk (DVD), high density floppydisks, or high density removable hard disk cartridges. Typically,library 12 does not have mixed media in it, but it is capable ofhandling such. Cartridges 77 are exported from library 12 in the +Xdirection, and imported in the −X direction. A robotic picker 79 (FIG.9) moves cartridges 77 to and from magazine 71 in the Y-Z plane.

[0037] When door 73 is open (FIG. 10), a user can manually insertcartridges 77 into or remove them from slots 75 in magazine 71 throughopening 64 in door 63. When door 73 is closed by the user, roboticpicker 79 can access the cartridges 77 placed into slots 75 (cartridgeimport). Alternately, when door 73 is closed, picker 79 can place morecartridges 77 into magazine 71 for removal from library 12 (cartridgeexport). Both of these operations are necessary since library 12 has afinite amount of cartridge storage space. Inactive cartridges whichstill contain valuable data are exported and shipped to a warehouse, thelowest tier in the data storage hierarchy. Each inactive cartridge isreplaced by a newly imported cartridge.

[0038] Referring now to FIGS. 11 and 12, a plurality of sensors 11 aremounted to an inner portion 81 of door 73 and, thus, rotatabletherewith. Sensors 11 are vertically arrayed to align with the slots 75of magazine 71 in a one-to-one ratio. Door 73 and sensors 11 pivotrelative to stationary magazine 71. Power to and electrical signals fromsensors 11 are transmitted on cable 83. Cable 83 also carries power to amotor 85 that opens and closes door 73. A master cable (not shown)extends from motor 85 and sensors 11 to controller 57. Door 73 allows auser to manually access cartridges 77 in library 12 through opening 64.

[0039] A bar coded label 87 is affixed to a rear side edge of eachcartridge 77. Labels 87 may also be located adjacent to cartridges 77near slots 75 (not shown). The lines of the bar code are parallel to theaxis of rotation of sensors 11. The orientation of the bar code linescauses the sensors 11 to sweep along a line perpendicular thereto. Inthe preferred embodiment, door 73 is pivoted and sensors 11 pivot pastthe rear side edges of stationary cartridges 77 to scan labels 87. It isthe swinging of door 73 which moves sensors 11, with their liquidcrystal lenses 13, 15, across the labels 87 which identifies cartridges77 in station 65 to controller 57. If the bar code reader cannot readthe code on a label 87, controller 57 changes the focal length of lenses13, 15 in the respective sensor 11 to focus the code image on thereader.

[0040] Alternatively, sensors 11 remain stationary and magazine 71 ispivoted about the Z-axis (FIG. 13) by motor 85. Sensors 11 read thebarcodes 87 (not shown) on the backs of cartridges 77 as magazine 71sweeps around. This alternate embodiment also utilizes a siding planardoor 89 rather than the cylindrical door 73 of the preferred embodiment.Door 89 may be configured to move or slide in either the Y-direction orin the Z-direction to allow a user to manually access cartridges 77through opening 64 in library 12. With both of these embodiments, thereis no mechanical motion of the components of sensor 11. Thus, the focusaction is always fast and responsive.

[0041] The information scanned from the cartridges 77 in magazine 71 isrelayed to controller 57 or a central data base for processing. Therobotic picker 79 would then move or handle individual cartridges 77based on instructions from controller 57. However, controller 57 mustidentify each cartridge 77 before giving commands to picker 79. Thus,controller 57 can give instructions to picker 79 as to which cartridges77 are to be stored in which slots 75 and which cartridges (if any) areto be directed into drives for immediate data I/O operations.

[0042] The invention has several advantages. The lens assembly usesliquid crystal lenses that can change their focal lengths at high speedsby merely varying an applied voltage in response to the focal lengthcontroller. The lens assembly is completely stationary and utilizes nomoving parts. This design is readily incorporated into automated storagelibraries having various configurations. The invention is well suitedfor libraries which contain various types of storage media or bar codelabels or differing sizes.

[0043] While the invention has been shown or described in only some ofits forms, it should be apparent to those skilled in the art that it isnot so limited, but is susceptible to various changes without departingfrom the scope of the invention.

We claim:
 1. An apparatus for identifying components, each having a label fixedly mounted in relation to the component and having information associated with the component, comprising: a first element having a plurality of storage positions that are adapted to support the components; a second element located adjacent to the first element, such that the first and second elements are movable relative to one another; a sensor mounted to the second element and having a light source and a variable focal length lens assembly that is adapted to read the labels associated with the components; and a controller connected to the sensor and at least one of the first and second elements for moving said one of the first and second elements relative to the other and adjusting the focal length of said lens assembly of the sensor to focus on and read the labels so that the information associated with their respective components may be processed by the controller:
 2. The apparatus of claim 1 , further comprising a picking device fixed mounted adjacent to the first element for moving the components in response to the controller processing the information.
 3. The apparatus of claim 1 wherein the sensor comprises a plurality of sensors that are equal in number to the number of storage positions of the first element, and wherein each of the sensors is aligned and associated with one of the storage positions.
 4. The apparatus of claim 1 wherein the second element is pivoted relative to the first element.
 5. The apparatus of claim 1 wherein the first element is pivoted relative to the second element.
 6. The apparatus of claim 1 wherein the first element is a stationary support structure and the second element is an arcuate door which is both manually and automatically operable relative to the stationary support structure.
 7. The apparatus of claim 1 wherein the storage positions of the first element are an array of parallel slots for supporting a plurality of the components in a one-to-one ratio.
 8. The apparatus of claim 1 wherein the lens assembly of the sensor has a focal length range of approximately 10 mm to infinity.
 9. The apparatus of claim 1 wherein the sensor is devoid of moving parts.
 10. The apparatus of claim 1 wherein the sensor is a bar code reader.
 11. The apparatus of claim 1 wherein the focal length of the lens assembly is altered by liquid crystal material.
 12. The apparatus of claim 1 wherein the lens assembly of the sensor comprises a pair of polarized liquid crystal lenses.
 13. The apparatus of claim 12 wherein the lenses are separated by a transparent spacer having a width equal to one-half wavelength of the light source of the sensor.
 14. The apparatus of claim 12 wherein each lens comprises a plurality of parallel substrates containing liquid crystal therebetween, each of the substrates having an electrode for applying a variable voltage to the liquid crystal located between said electrode and an adjacent electrode for altering the refractive index of the liquid crystal and, thus, the focal length of the lens assembly.
 15. The apparatus of claim 14 wherein each of the substrates is coated with an alignment material.
 16. The apparatus of claim 15 wherein the alignment material has been processed to set a desired alignment direction for the liquid crystal.
 17. The apparatus of claim 14 wherein adjacent ones of the substrates are equally spaced apart by a distance in the range of 30 to 70 microns.
 18. The apparatus of claim 14 wherein each of the substrates has a thickness of approximately 2 microns and a width of approximately 70 microns.
 19. The apparatus of claim 14 wherein the electrodes on the substrates are generally arcuate in shape.
 20. An automated media storage library having a base with a media drive unit and a picking device for interacting with data storage devices located therein, each of the data storage devices having a label fixedly mounted in relation thereto and having information associated with its respective data storage device, the library comprising: an input/output station mounted to the base and having a scanner and a magazine with a plurality of storage positions that are adapted to contain the data storage devices, the scanner and the magazine being movable relative to one another; the scanner having a sensor mounted thereto with a light source and a variable focal length lens assembly that is adapted to read the labels associated with the data storage devices; a controller adapted to be connected to the media drive unit, the picking device, and the input/output station for moving one of the scanner and the magazine relative to the other and adjusting the focal length of said lens assembly to focus on and read the labels so that the information associated with their respective data storage devices may be processed by the controller; and wherein the picking device moves selected ones of the data storage devices from said positions of the magazine to the media drive unit in response thereto.
 21. The library of claim 20 wherein the scanner comprises a plurality of sensors which are equal in number to the number of positions in the magazine, and wherein each of the sensors is aligned and associated with one of the positions.
 22. The library of claim 20 wherein the scanner is pivoted relative to the magazine.
 23. The library of claim 20 wherein the magazine is pivoted relative to the scanner.
 24. The library of claim 20 wherein the scanner is an arcuate door which is both manually and automatically operable relative to the magazine.
 25. The library of claim 20 wherein the input/output station is mounted inside the base and is manually accessible from an exterior of the base.
 26. The library of claim 20 wherein the lens assembly of the sensor has a focal length range of approximately 10 mm to infinity.
 27. The library of claim 20 wherein the scanner is a bar code reader.
 28. The library of claim 20 wherein the focal length of the lens assembly is altered with liquid crystal material.
 29. The library of claim 20 wherein the lens assembly of is the sensor comprises a pair of polarized liquid crystal lenses.
 30. The library of claim 29 wherein the pair of lenses are separated by a transparent spacer having a width equal to one-half wavelength of the light source of the sensor.
 31. The library of claim 29 wherein each lens comprises a plurality of parallel substrates containing liquid crystal therebetween, each of the substrates having an electrode for applying a variable voltage to the liquid crystal located between said electrode and an adjacent electrode for altering the refractive index of the liquid crystal and, thus, the focal length of the lens assembly.
 32. The library of claim 31 wherein each of the substrates is coated with an alignment material.
 33. The library of claim 32 wherein the alignment material has been processed to set a desired alignment direction for the liquid crystal.
 34. The library of claim 31 wherein adjacent ones of the substrates are equally spaced apart by a distance in the range of 30 to 70 microns.
 35. The library of claim 31 wherein each of the substrates has a thickness of approximately 2 microns and a width of approximately 70 microns.
 36. The library of claim 31 wherein the electrodes on the substrates are generally arcuate in shape.
 37. An automated media storage library having a base with a media drive unit and a picking device for interacting with data storage devices located therein, each of the data storage devices having a label fixedly mounted in relation thereto and having information associated with its respective data storage device, the library comprising: an input/output station mounted to the base and having a scanner and a magazine with a plurality of storage positions that are adapted to contain the data storage devices, the scanner being pivotable relative to the magazine; the scanner having a plurality of sensors mounted thereto, each having a light source and a variable focal length lens assembly that is adapted to read the labels associated with the data storage devices, the sensors being equal in number to the number of positions in the magazine, and wherein each of the sensors is aligned and associated with one of the positions; a controller adapted to be connected to the media drive unit, the picking device, and the input/output station for moving the scanner relative to the magazine and adjusting the focal lengths of said lens assemblies to focus on and read the labels so that the information associated with their respective data storage devices may be processed by the controller; and wherein the picking device moves selected ones of the data storage devices from said positions of the magazine to the media drive unit in response thereto.
 38. The library of claim 37 wherein the scanner is an arcuate door which is both manually and automatically operable relative to the magazine.
 39. The library of claim 37 wherein each of the lens assemblies has a focal length range of approximately 10 mm to infinity.
 40. The library of claim 37 wherein the scanner is a bar code reader.
 41. The library of claim 37 wherein the focal lengths of the lens assemblies are altered with liquid crystal material.
 42. The library of claim 37 wherein each of the lens assemblies comprises a pair of polarized liquid crystal lenses.
 43. The library of claim 42 wherein each pair of lenses is separated by a transparent spacer having a width equal to one-half wavelength of the light sources.
 44. The library of claim 42 wherein each lens comprises a plurality of parallel substrates containing liquid crystal therebetween, each of the substrates having an electrode for applying a variable voltage to the liquid crystal located between said electrode and an adjacent electrode for altering the refractive index of the liquid crystal and, thus, the focal lengths of the lens assemblies.
 45. The library of claim 44 wherein each of the substrates is coated with an alignment material.
 46. The library of claim 45 wherein the alignment material has been processed to set a desired alignment direction for the liquid crystal.
 47. The library of claim 44 wherein adjacent ones of the substrates are equally spaced apart by a distance in the range of 30 to 70 microns.
 48. The library of claim 44 wherein the electrodes on the substrates are generally arcuate in shape.
 49. An automated media storage library having a base with a media drive unit and a picking device for interacting with data storage devices located therein, each of the data storage devices having a label fixedly mounted in relation thereto and having information associated with its respective data storage device, the library comprising: an input/output station mounted to the base and having a door and a magazine with a plurality of storage slots that are adapted to contain the data storage devices, the door being pivotable relative to the magazine; the door having a plurality of sensors mounted thereto, each having a light source and a variable focal length lens assembly with a pair of liquid crystal lenses that are adapted to read the labels associated with the data storage devices, the sensors being equal in number to the number of slots in the magazine, and wherein each of the sensors is aligned and associated with one of the slots; each lens comprising a plurality of parallel substrates containing liquid crystal therebetween, each of the substrates having an electrode for applying a variable voltage to the liquid crystal located between said electrode and an adjacent electrode for altering the refractive index of the liquid crystal and, thus, the focal lengths of the lens assemblies; a controller adapted to be connected to the media drive unit, the picking device, and the input/output station for moving the door relative to the magazine and adjusting the focal lengths of the lens assemblies to focus on and read the labels so that the information associated with their respective data storage devices may be processed by the controller; and wherein the picking device moves selected ones of the data storage devices from said slots of the magazine to the media drive unit in response thereto.
 50. The library of claim 49 wherein the door is both manually and automatically pivotable relative to the magazine.
 51. The library of claim 49 wherein each of the lens assemblies has a focal length range of approximately 10 mm to infinity.
 52. The library of claim 49 wherein each pair of lenses is separated by a transparent spacer having a width equal to one-half wavelength of the light sources.
 53. The library of claim 49 wherein each of the substrates is coated with an alignment material that has been processed to set a desired alignment direction for the liquid crystal.
 54. The library of claim 49 wherein adjacent ones of the substrates are equally spaced apart by a distance in the range of 30 to 70 microns.
 55. The library of claim 49 wherein the electrodes on the substrates are generally arcuate in shape. 